Mine is neither, but it is the old style. It taps into the brake light, and you set the strength. Either on or off with the brake lights, but variable strength. It works, but depending on weather and road surface, I've had trailer wheels lock up. It can be jerky too. I've got a pintle hitch.
If you feel like spending the money, I've sure the new fancy ones that have a gyroscope or pendulum thing in them are nice, they work by g-force, the harder you brake the stronger they apply the trailer. I'm sure it's much smoother. I believe there is still a range adjustment, but it's not on/off like mine.